Purification of Titanium Tetrachloride

ABSTRACT

Disclosed is a process/system for the removal of metal chloride impurities from a titanium tetrachloride stream. The metal chloride impurities are removed through contact of the titanium tetrachloride stream with a sorbent material comprising a member selected from the group consisting of an alumino-silicate, activated alumina, ultrafine TiO2, and combinations thereof.

1. FIELD OF THE INVENTION

The presently disclosed and claimed inventive process(es), procedure(s), method(s), product(s), result(s) and/or concept(s) (collectively hereinafter referenced to as the “presently disclosed and claimed inventive concept(s)”) relates generally to processes and systems for purifying titanium tetrachloride. More specifically, the presently disclosed and claimed inventive concept(s) relates to the removal of chloride or oxychloride metal contaminants from titanium tetrachloride using a sorbent material.

2. DESCRIPTION OF THE RELATED ART

Titanium tetrachloride (TiCl₄) is produced from the chlorination of titaniferous ores. The manufacture of high purity TiCl₄ has become more challenging due to the limited supply, and resulting high costs, of high purity titanium ores. While the use of lower cost and more abundant lower grade ores would be preferable, such would require additional steps or unit operations, such as more extensive distillation, to manufacture the same purity of TiCl₄. It is generally desirable to keep this purification process simple and of low cost.

There is also a need for purification of lower grade (merchant) TiCl₄ produced from lower grade ores to remove corrosive metal chlorides or oxychlorides, such as SnCl₄ and SnCl₂ (tin chlorides).

The common art teaches the use of high surface area absorbers like activated carbon to remove contaminants, but it has been found that tin chlorides are not removed effectively using activated carbon.

Accordingly, there remains a need for an improved process and system for purifying either high or merchant grade TiCl₄ to remove metal chloride and oxychloride contaminants, and which can be tailored for removal of specific contaminants of concern.

SUMMARY OF THE INVENTION

In accordance with an embodiment of the presently disclosed and claimed inventive concept(s), a titanium tetrachloride purification process is provided. The process comprises:

a) contacting a sorbent material with a feedstock comprising titanium tetrachloride and at least one impurity to form a product stream, wherein the sorbent material comprises a member selected from the group consisting of an alumino-silicate, activated alumina, ultrafine TiO2, and combinations thereof, and wherein the at least one impurity comprises a member selected from the group consisting of carbonyl sulfide, sulfur dioxide, phosgene, hydrogen sulfide, carbon disulfide, chlorides of: aluminum, carbon, gallium, indium, tin, thallium, lead, bismuth, polonium, boron, silicon, germanium, arsenic, antimony, tellurium, zirconium, hafnium, iron, chromium, copper, magnesium, vanadium, nickel, thorium, uranium, oxychlorides of: aluminum, bismuth, arsenic, antimony, zirconium, hafnium, chromium, vanadium, uranium; and combinations thereof; and b) withdrawing the product stream. Optionally, the sorbent material, upon becoming spent, can be regenerated for further use in the removal of impurities from the feedstock.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chart showing % impurity removal from TiCl₄ for various zeolites and impurities.

DETAILED DESCRIPTION OF THE INVENTION

Before explaining at least one embodiment of the inventive concept(s) disclosed herein in detail, it is to be understood that the presently disclosed and claimed inventive concept(s), process(es), methodology(ies) and/or outcome(s) is not limited in its application to the details of construction and the arrangement of the components or steps or methodologies set forth in the following description or illustrated in the drawings. The presently disclosed and claimed inventive concept(s), process(es), methodology(ies) and/or outcome(s) disclosed herein is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting the presently disclosed and claimed inventive concept(s), process(es), methodology(ies) and/or outcome(s) herein in any way. All terms used herein are intended to have their ordinary meaning unless otherwise provided.

The titaniferous ores useful in the presently disclosed and claimed inventive concept(s) can be any titaniferous ores capable of being chlorinated to produce sufficient quantities of TiCl₄.

A feedstock comprising titanium tetrachloride and at least one impurity can be contacted, preferably in a contacting vessel, with a sorbent material comprising a member selected from the group consisting of an alumino-silicate, activated alumina, ultrafine TiO2, and combinations thereof to form a product stream. The sorbent material can further comprise activated carbon. The at least one impurity can be any impurity commonly present in a titanium tetrachloride stream obtained from the chlorination of a titaniferous ore. In an embodiment, impurities include or comprise carbonyl sulfide, sulfur dioxide, phosgene, hydrogen sulfide, carbon disulfide, chlorides of: aluminum, carbon, gallium, indium, tin, thallium, lead, bismuth, polonium, boron, silicon, germanium, arsenic, antimony, tellurium, zirconium, hafnium, iron, chromium, copper, magnesium, vanadium, nickel, thorium, uranium, and oxychlorides of: aluminum, bismuth, arsenic, antimony, zirconium, hafnium, chromium, vanadium, uranium, either individually or in combination of two or more thereof and combinations thereof. In a particular embodiment, chlorides of tin are generally present as an impurity in the form of SnCl₄, but can also include SnCl₂. The product stream is then withdrawn from the contacting vessel.

It should be understood that embodiments of the invention are not restricted to a particular form of feedstock and the feedstock may be in various forms. For example, the feedstock may be in the form of a vapor or liquid, either individually or in a combination thereof. In accordance with one embodiment, the titanium tetrachloride comprises an anhydrous form when contacted with the alumino-silicate. In accordance with another embodiment, the titanium tetrachloride comprises an aqueous form when contacted with the alumino-silicate.

The at least one impurity can be present in the feedstock in the range of from about 0.1 to about 10,000 ppmw, or from about 5 to about 1000 ppmw.

The resulting product stream can contain less than about 80 weight %, or less than about 50 weight %, or less than about 20 weight % of the impurity(ies) contained in the feedstock.

More particularly, in an embodiment impurities include or comprise chlorides of tin, arsenic, antimony, zirconium, and oxychlorides of arsenic, antimony, zirconium, either individually or in combinations of two or more thereof.

The feedstock can comprise in the range of from about 1 to about 500 ppmw, or from about 1 to about 200 ppmw, of combined chlorides of tin comprising tin dichloride. The product stream can contain less than about 20 weight %, or less than about 10 weight %, of the tin dichloride contained in the feedstock.

The feedstock can comprise in the range of from about 0.1 to about 500, or from about 1 to about 200 ppmw, or from about 0.1 to about 20 ppmw, of combined chlorides and oxychlorides of arsenic. The product stream can contain less than about 20 weight %, or less than about 10 weight %, of the combined chlorides and oxychlorides of arsenic contained in the feedstock.

The feedstock can comprise in the range of from about 0.1 to about 500, or from about 1 to about 200 ppmw, or from about 0.1 to about 20 ppmw, of combined chlorides and oxychlorides of antimony. The product stream can contain less than about 20 weight %, or less than about 10 weight %, of the combined chlorides and oxychlorides of antimony contained in the feedstock.

The feedstock can comprise in the range of from about 0.1 to about 100 ppmw, or from about 0.1 to about 10 ppmw, of combined chlorides and oxychlorides of zirconium. The product stream can contain less than about 20 weight %, or less than about 10 weight %, of the combined chlorides and oxychlorides of zirconium contained in the feedstock.

The alumino-silicate can have a surface area greater than about 200 m²/g, or greater than about 600 m²/g. Also, the alumino-silicate can have an average channel size in the range of from about 4.5 to about 9.5 Å, or in the range of from about 6.5 to about 7.5 Å; and can have an alkali content in the range of from about 0.02 to about 0.2 wt %, or in the range of from about 0.025 to about 0.04.

Further, the silica to alumina ratio of the alumino-silicate can be in the range of from about 30 to about 100, or from about 60 to about 85. More particularly, the alumino-silicate includes or comprises a zeolite material, more particularly a faujasite zeolite.

The contacting of the sorbent material with the feedstock can comprise contacting the sorbent material with the feedstock in a single vessel; removing the sorbent material from the vessel; and disposing the sorbent material once spent. This cycle can then be repeated.

The contacting of the sorbent material with the feedstock can comprise i) contacting the sorbent material with the feedstock in a single vessel until the sorbent material is spent forming a spent sorbent material; stopping contact with the feedstock in step a) until the spent sorbent material is regenerated into a regenerated sorbent material; and iii) contacting the regenerated sorbent material with the feedstock. This cycle can then be repeated.

The contacting of the sorbent material with the feedstock can comprise contacting the sorbent material with the feedstock in a system containing multiple vessels, and wherein the contacting of the sorbent material with the feedstock can comprise sequentially charging the feedstock to the vessels and regenerating the sorbent material in each of the vessels upon becoming spent. This cycle can then be repeated.

The regeneration of the sorbent material can be accomplished by contacting the spent sorbent material with a flow of either inert gas or TiCl₄, or mixtures thereof, at elevated temperatures.

A titanium ore of relatively low grade, such as, but not limited to, a titanium ore comprising titanium oxide, iron oxide, and at least 3 wt %, or at least 4 wt %, of the at least one impurity, can be chlorinated to form the feedstock.

The product stream can be reacted with oxygen to form pigmentary titanium dioxide. The product stream can also be reacted with a metal selected from the group consisting of sodium, magnesium, or combinations thereof, to form titanium metal.

When the sorbent material comprises an alumino-silicate, the alumino-silicate can be selected for the removal of a specific one of the impurities or specific groups of the impurities based on: i) the geometric size of the impurity or impurities, ii) the channel size of the alumino-silicate material, iii) at least one property of the alumino-silicate material such as, but not limited to, polarity, and iv) combinations thereof. For example, Table 1 lists approximate molecular diameters for various impurities, for titanium tetrachloride, and the approximate average channel size for a faujasite zeolite (FAU).

TABLE 1  ZrCl₄~6.8 Å AsCl₃~6.4 Å  SnCl₂~6.6 Å TiCl₄~6.4 Å SnCl₄~6.8 Å  FAU~7.4 Å

EXAMPLES

Quantities of titanium tetrachloride were each separately doped with an impurity. The doped samples were then each separately contacted with a faujasite-type zeolite obtained from Zeolyst International, described as follows:

Zeolite 1—Product designation CP 811C-300 Zeolite 2—Product designation CP 814C Zeolite 3—Product designation CBV-901

The samples were contacted with the zeolites in the form of anhydrous liquids. The initial and final concentrations of the impurities were measured, and the results of such testing are shown in Table 2.

TABLE 2 Faujasite Initial Impurity Final Impurity Impurity Zeolite Conc., ppmw Conc., ppmw % Change ZrCl₄ 1 70.36 3.47 95.0 ZrCl₄ 2 70.36 0.296 99.6 ZrCl₄ 3 3.3 0.41 87.7 SnCl₂ 1 93 26 72.0 SnCl₂ 2 93 2 97.9 SnCl₄ 1 139 120 13.7 SnCl₄ 2 139 125 10.1 SnCl₄ 3 77.5 76.5 1.24 AsCl₃ 1 19.0 1.44 92 AsCl₃ 2 19.0 5.92 68.8 AsCl₃ 3 5.53 5.64 0 SbCl₃ 1 157.0 95.0 54.2 SbCl₃ 2 157.0 109.0 34.2 SbCl₅ 3 25.0 23.5 6.1

As can be seen from the results presented in Table 2, contacting metal chloride contaminated titanium tetrachloride with a sorbent material in accordance with an embodiment of the presently disclosed and claimed inventive concept(s) results in a significant decrease in the concentrations of such impurities. Also, as is more clearly shown in FIG. 1, the plot of removal efficiency of the zeolite choices across the different impurities reveals a wide variability, and the opportunity to tailor a system/process utilizing a specific zeolite, or mix of zeolites, to accomplish a targeted removal efficiency for specific impurities.

Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by anyone of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Further, unless expressly stated otherwise, the term “about” as used herein is intended to include and take into account variations due to manufacturing tolerances and/or variabilities in process control.

Changes may be made in the construction and the operation of the various components, elements and assemblies described herein, and changes may be made in the steps or sequence of steps of the methods described herein without departing from the spirit and the scope of the presently disclosed and claimed inventive concept(s) as defined in the following claims. 

What is claimed is:
 1. A titanium tetrachloride purification process comprising the steps of: a) contacting a sorbent material with a feedstock comprising titanium tetrachloride and at least one impurity to form a product stream, wherein said sorbent material comprises a member selected from the group consisting of an alumino-silicate, activated alumina, ultrafine TiO2, and combinations thereof, and wherein said at least one impurity comprises a member selected from the group consisting of carbonyl sulfide, sulfur dioxide, phosgene, hydrogen sulfide, carbon disulfide, chlorides of: aluminum, carbon, gallium, indium, tin, thallium, lead, bismuth, polonium, boron, silicon, germanium, arsenic, antimony, tellurium, zirconium, hafnium, iron, chromium, copper, magnesium, vanadium, nickel, thorium, uranium, oxychlorides of: aluminum, bismuth, arsenic, antimony, zirconium, hafnium, chromium, vanadium, uranium; and combinations thereof; and b) withdrawing said product stream.
 2. The process of claim 1 wherein said sorbent material further comprises activated carbon.
 3. The process of claim 1 wherein said member of said sorbent material comprises alumino-silicate and said sorbent material further comprises activated carbon.
 4. The process of claim 1 wherein said feedstock comprises a vaporous form.
 5. The process of claim 1 wherein said feedstock comprises a liquid form.
 6. The process of claim 1 wherein said titanium tetrachloride comprises an anhydrous form.
 7. The process of claim 1 wherein said titanium tetrachloride comprises an aqueous form.
 8. The process of claim 1 wherein said feedstock comprises in the range of from about 0.1 to about 10,000 ppmw of said at least one impurity.
 9. The process of claim 8 wherein said product stream contains less than about 80 weight % of said at least one impurity contained in said feedstock.
 10. The process of claim 1 wherein said at least one impurity comprises a chloride of tin comprising tin dichloride; and wherein said feedstock comprises in the range of from about 1 to about 500 ppmw of combined chlorides of tin.
 11. The process of claim 10 wherein said product stream contains less than about 20 weight % of the tin dichloride contained in said feedstock.
 12. The process of claim 1 wherein said at least one impurity comprises a member selected from the group consisting of chlorides of arsenic, oxychlorides of arsenic, and combinations thereof; and wherein said feedstock comprises in the range of from about 0.1 to about 500 ppmw of combined chlorides of arsenic and oxychlorides of arsenic.
 13. The process of claim 12 wherein said product stream contains less than about 20 weight % of the combined chlorides of arsenic, and oxychlorides of arsenic contained in said feedstock.
 14. The process of claim 1 wherein said at least one impurity comprises a member selected from the group consisting of chlorides of antimony, oxychlorides of antimony, and combinations thereof; and wherein said feedstock comprises in the range of from about 0.1 to about 500 ppmw of combined chlorides of antimony and oxychlorides of antimony.
 15. The process of claim 14 wherein said product stream contains less than about 20 weight % of the combined chlorides of antimony and oxychlorides of antimony contained in said feedstock.
 16. The process of claim 1 wherein said at least one impurity comprises a member selected from the group consisting of chlorides of zirconium, oxychlorides of zirconium, and combinations thereof; and wherein said feedstock comprises in the range of from about 0.1 to about 100 ppmw of combined chlorides of zirconium and oxychlorides of zirconium.
 17. The process of claim 16 wherein said product stream contains less than about 20 weight % of the combined chlorides of zirconium and oxychlorides of zirconium contained in said feedstock.
 18. The process of claim 1 wherein contacting said sorbent material with said feedstock comprising titanium tetrachloride and at least one impurity comprises contacting said sorbent material with said feedstock in a single vessel; removing said sorbent material from said vessel; and disposing said sorbent material once spent.
 19. The process of claim 1 wherein contacting said sorbent material with said feedstock comprising titanium tetrachloride and at least one impurity comprises i) contacting said sorbent material with said feedstock in a single vessel until said sorbent material is spent forming a spent sorbent material; stopping contact with said feedstock in step a) until said spent sorbent material is regenerated into a regenerated sorbent material; and iii) contacting the regenerated sorbent material with said feedstock.
 20. The process of claim 1 wherein contacting said sorbent material with said feedstock comprising titanium tetrachloride and at least one impurity comprises contacting said sorbent material with said feedstock in a system containing multiple vessels, and wherein said contacting of said sorbent material with said feedstock comprises sequentially charging said feedstock to said vessels and regenerating said sorbent material in each of said vessels upon becoming spent.
 21. The process of claim 1 further comprising chlorinating a titanium ore comprising titanium oxide, iron oxide, and at least 3 wt % of said at least one impurity to form said feedstock.
 22. The process of claim 1, further comprising reacting said product stream with oxygen to form pigmentary titanium dioxide.
 23. The process of claim 1, further comprising reacting said product stream with a metal selected from the group consisting of sodium, magnesium, or combinations thereof, to form titanium metal.
 24. A titanium tetrachloride purification process comprising the steps of: a) contacting a feedstock comprising titanium tetrachloride and at least one impurity with an alumino-silicate to form a product stream, wherein said at least one impurity comprises a member selected from the group consisting of carbonyl sulfide, sulfur dioxide, phosgene, hydrogen sulfide, carbon disulfide, and chlorides of: aluminum, carbon, gallium, indium, tin, thallium, lead, bismuth, polonium, boron, silicon, germanium, arsenic, antimony, tellurium, zirconium, hafnium, iron, chromium, copper, magnesium, vanadium, nickel, thorium, uranium, oxychlorides of: aluminum, bismuth, arsenic, antimony, zirconium, hafnium, chromium, vanadium, uranium; and combinations thereof; and b) withdrawing said product stream.
 25. The process of claim 24 wherein said alumino-silicate has a surface area greater than about 200 m²/g.
 26. The process of claim 24 wherein said alumino-silicate has an average channel size in the range of from about 4.5 to about 9.5 Å.
 27. The process of claim 24 wherein said alumino-silicate has an alkali content in the range of from about 0.02 to about 0.2 wt %.
 28. The process of claim 24 wherein said alumino-silicate has a silica to alumina ratio in the range of from about 30 to about
 100. 29. The process of claim 24 wherein said alumino-silicate comprises a zeolite.
 30. The process of claim 29 wherein said zeolite comprises a faujasite zeolite. 